People take advantage of the warm weather in San Francisco on Friday, February 2, 2018 after tempertures reached into the 70s. Brian Feulner, Special to the Chronicle

People take advantage of the warm weather in San Francisco on Friday, February 2, 2018 after tempertures reached into the 70s. Brian Feulner, Special to the Chronicle

Photo: Brian Feulner, Special To The Chronicle

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People picnic at the coservatory of flowers Friday, Febrary 2, 2018 as Tempertures in San Francisco reached into the 70s. Brian Feulner, Special to the Chronicle

People picnic at the coservatory of flowers Friday, Febrary 2, 2018 as Tempertures in San Francisco reached into the 70s. Brian Feulner, Special to the Chronicle

Photo: Brian Feulner, Special To The Chronicle

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A beautiful day for fishing at Los Vaqueros Reservoir in Brentwood, Calif., on Friday Feb. 2, 2018.

A beautiful day for fishing at Los Vaqueros Reservoir in Brentwood, Calif., on Friday Feb. 2, 2018.

Photo: Michael Macor, The Chronicle

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People take advantage of the warm weather in San Francisco on Friday, February 2, 2018 after tempertures reached into the 70s. Brian Feulner, Special to the Chronicle

People take advantage of the warm weather in San Francisco on Friday, February 2, 2018 after tempertures reached into the 70s. Brian Feulner, Special to the Chronicle

Photo: Brian Feulner, Special To The Chronicle

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San Francisco Bay Area bakes amid record-breaking temperatures

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A high-pressure system off the West Coast sent the mercury rising in the San Francisco Bay Area Friday with temperatures 10 to 20 degrees above normal and breaking records across the region. The spring-like weather is expected to continue through the weekend and beyond.

San Francisco Airport hit 73 degrees Friday afternoon, breaking the same-day 1995 record of 69. Kentfield reached 72, surpassing the 2005 record of 71. And San Jose spiked at 76, rising above the 1963 record of 73.

The weekend will bring the same sunny, hot weather with highs in the 70s; Oakland and San Francisco Airports are expected to hit highs of 70 Saturday, and San Jose a high of 76 degrees. Northeast of the Bay Area, Pinnacles National Monument could be a balmy 82 degrees (bring extra water if you're planning to hike there).

The region has seen unseasonably warm, dry weather in the past week and the conditions are expected to continue at least into the first two weeks of February.

"It's anomalously warm and it's expected to continue for the foreseeable future," says Scott Rowe, a forecaster with the National Weather Service office in Monterey. "I was looking at the forecast models this morning, and I'm still not seeing any wet weather."

Amid a torrent of rain, the Russian River swelled to its highest level in a decade on Jan. 11, 2017, forcing hundreds of people in and around Sonoma County and the town of Guerneville to flee to higher ground, often by boat, the SF Chronicle reported. The river flooded again in February. (Photo: Dustin Coupe is surprised to find out the phone is working as he paddles on a kayak home along River Road during the Russian River flood on Wednesday, Jan. 11, 2017 in Guerneville.)

Storms pummeled the Sierra at the start of the year and by Jan. 23 the snowpack above 6,000 feet was around 10 feet and up to 20 feet at the highest peaks. The Northern Sierra–Trinity snowpack was 158 percent of average. "This winter is just pretty much crushing a lot of records we've had around the region," said Chris Smallcomb, a meteorologist with the National Weather Service's Reno office. "When we look at the Northern Sierra, we're seeing numbers like we did during the 1983 El Niño winter." (Photo: A car is seen buried in snow at Squaw Ski Resort in North Lake Tahoe, California on January 27, 2017.)

Back-to-back storms pummeled Northern California in January, but despite the downpours, only one rainfall record was broken among the 62 gauges spread throughout the area.
The Lick Observatory atop Mount Hamilton in San Jose saw 14.78 inches, marking its wettest January in its recorded history that goes back 120 years.
Outside the Bay Area in nearby Santa Cruz County, Ben Lomond also saw its wettest start to the year. The gauge recorded 32.74 inches in January, breaking the previous record of 32.41 inches set in 1940. January 2017 was the sixth-wettest for Downtown San Francisco.

Yosemite Creek operated a bit like a Slurpee machine in late January.
The swollen waterway collected fallen snow at the top of Yosemite Falls and then dropped the slush 2,425 feet down the waterfall into the pool below before it continues to flow down the creek.
The soft, amorphous ice that's formed by the accumulation of ice crystals in water is known as frazil ice. Because it's moving turbulently down the creek, it never freezes solid.
Yosemite National Park spokesperson Scott Gediman said the conditions were perfect for frazil ice throughout January.
"We've had so much snow, and now we're getting the freezing conditions," Gediman said. "Daytime temps have been in the low 30s; overnight in the 20s, other morning it was 26 degrees when I came into work at 7:30."

Monterey Bay recorded the largest waves it has seen in 30 years with the swell reaching 34.12 feet at one point. The previous record was 32.8 feet in 2008. The S.S. Palo Alto, otherwise known as the 'Concrete Ship,' was tossed and broken up by high waves in the bay in January.

Atmospheric river causes widespread flooding in Marin County in February 2017

The National Weather Service issued flash flood warnings for parts of Marin, Sonoma and Napa counties on Feb. 7, 2017. Areas of San Anselmo were evacuated. Sir Francis Drake Boulevard was flooded in both the eastbound and westbound directions in the area of the Bon Air Center shopping center in Greenbrae. (Photo: Flooding along Center Road in San Anselmo, Calif., on Feb. 7, 2017.)

A gaping hole was discovered in the Oroville Dam main spillway on Feb. 7, 2017, marking the start of a catastrophic situation that unfolded over the course of several weeks.
As a moisture-packed storm drenched Northern California in early February, a torrent of stormwater and snow melt poured into Lake Oroville. The lake level rose rapidly and Oroville reached full capacity.
To make room in the reservoir and prevent flooding, water was released down the main spillway, a 3,000-foot-long concrete chute that dumps water into the Feather River. When the crater was discovered on the main spillway, dam operators monitored the situation carefully, reducing the flow to prevent the main spillway from becoming further damaged and inoperable. But they couldn't prevent further erosion and the hole grew into a massive crater.

The road was closed on and off throughout the rainy season due to heavy rain and flooding.

Highway 37 closes multiple times in February 2017 due to flooding

The road was closed on and off throughout the rainy season due to heavy rain and flooding.

Photo: Josh Edelson, JOSH EDELSON / SAN FRANCISCO CHRONICLE

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Lake Berryessa's Glory Hole spills over for the first time in 10 years in February 2017

The reservoir two hours north of San Francisco reached full capacity and an elevation level of 440 feet on Feb. 17 at 6 a.m., and began spilling.
The unique spillway operates similarly to a bathtub drain, but in this case the drain isn't at the bottom of the tub and is instead located near the top.

In the first three weeks of January alone, the Lake Tahoe area received nearly a full winter's worth of snow, according to the Reno Gazette-Journal. Houses were buried, cars blanketed and driveways covered.
And then came February, and the Sierra Nevada was slammed yet again with moisture-packed storms fueled by atmospheric rivers.
"We usually see three or four atmospheric rivers in a season," said Scott McGuire, a meteorologist with the National Weather Service office in Reno. "We've already had 10. We've had so much snow to the point where it's getting hard to measure." (Photo: The top of the Dipper Chair at Heavenly on Feb. 22, 2017.)

The dark emerald green waters of the Bay turned a murky brown as fine sediment washed by back-to-back storms from the slopes of the Sierra Nevada and the soils of the Central Valley and into rivers. These rivers were swollen and roaring from the heavy rains and their high flows whisk along the fine particles that are heavier than water.
They carry the fine silt into the Bay where its dumped along with surges of fresh water and is further stirred up by wind, tides and wave action.
A pair of before-and-after photos of the Bay, taken by a NASA satellite in April 2016 and February 2017 (above), show that sediment was floating around the waters of the northern half of the Bay and is fanning out under the Golden Gate Bridge into the Pacific Ocean.
"These photos are great because you're seeing this once-a-decade kind of event when we get very large flows on the two main rivers of the Central Valley — the Sacramento and the San Joaquin," said Jeffrey Mount, a senior fellow with the Public Policy Institute of California. "When these flows are high, they carry high amounts of very fine clay sized particles. That's what you're seeing."
Satellite images taken by NASA in April 2016 (right) and February 2017 show the impact of rivers dumping fresh water and sediment into San Francisco Bay.

Four Big Sur state parks shutter due to winter storms and summer wildfires in winter 2017

The brutal combination of summer wildfires and winter storms damaged the infrastructure at several parks perched along Big Sur's dramatic coastline. Andrew Molera and Julia Pfeiffer Burns were both closed while Garrapata, Limekiln and Pfeiffer Big Sur had limited areas closed. Some areas of the parks remain closed: Garrapate State Park is open on the west side of Highway 1 and closed to public entry on the east side. Pine Ridge Trail and Sykes Hot Springs are closed indefinitely. Julia Pfeiffer Burns State Park is open for limited day use; the campground is closed.

Cracks appear in the Pfeiffer Canyon Bridge in Big Sur in February 2017

On Feb. 11, a person walking under the bridge noticed fractures in one of the pillars and the ground under the base was washing out from underneath. Caltrans closed the bridge to traffic on Feb. 15 as the cracks worsened and the structure was declared damaged beyond repair. "Due to extreme safety concerns and the bridge's dynamic instability, everyone needs to stay clear and not get within 100 feet of either side of the bridge," a statement from the government agency reads. A new steel bridge was opened on Oct. 13.

California's total reservoir storage reaches 110 percent of average in March 2017

Amid a rainy season marked by ceaseless moisture-packed storms, the same reservoirs that were near empty during the drought are filled with water and 100 to 170 percent of their historical averages. Brimming and replenished, they became a symbol of the state's recovery.

The velvety green slopes of the Tehachapi Mountains were covered in bright orange patches of California poppies in late winter. Extraordinary blooms like the display on the Grapevine are becoming less common. Invasive species are overtaking the California wildflowers, and in the Tehachapi range, red brome and ripgut brome have dominated since the 1960s, suppressing the native California poppy. "During droughts, the invasive species don't reach reproductive maturity and they die and their seeds are knocked out," said Richard Minnich, a professor of geography in the Earth Sciences Department at the University of California, Riverside. "The wildflowers have a long seed life and their seeds survive the drought. And then the wet years come and the poppies don't have interference and then they have their great moment."

On April 7, Brown declared an official end to California's drought emergency after months of storms filled reservoirs and piled up the snowpack. The move did away with a 2014 order that ushered in a period of unprecedented water rationing across the state.

Spring Break is a whiteout as snowstorms continue to wallop the Sierra into April 2017

Families on spring break in Tahoe in early April didn't find sun-drenched slopes and bluebird skies.
Mother Nature blasted the region, bringing nearly 30 inches of fresh powder to many resorts across three days in the first week of the month. Strong winds slammed the area, with gusts over 100 miles per hour whipping the highest mountain peaks. (Photo: A Caltrans worker makes an on-the-spot repair to a piece of snow removal equipment on SR-108 over Sonora Pass in Tuolumne County in April 2017.:

On April 17, the National Weather Service (NWS) office in Sacramento announced that the 2016-17 water year marked the wettest year for the northern Sierra in recorded history. Well above the values registered back in 1982-83 during one of the strongest El Niño events on record.

Carrizo Plain National Monument, a five-hour drive from San Francisco, had the season's best floral display. Orange, yellow and purple wildflowers painted the hills. After years of drought an explosion of wildflowers in Southern and Central California drew record crowds to see the rare abundance of color called a super bloom.

A swath of the hillside gave way in an area called Mud Creek on Saturday, May 20, 2017 covering about one-third of a mile, half a kilometer, of road and changing the Big Sur coastline. This aerial photo taken May 22, 2017 shows the massive landslide along California's coastal Highway 1 that buried the road under a 40-foot layer of rock and dirt.

A late spring storm churned waves up to five to six feet on Lake Tahoe "It's not uncommon to have four to five footers on the lake," said Luke Berghuis, a petty officer first class with the Coast Guard in Tahoe City. "But wow, a whole week of waves this big is unusual. And because the lake is so full, the waves look especially big." Photo taken by Christi Virdee on June 10, 2017

In a somewhat rare event for June, snow was seen around lake Tahoe on the morning of June 17, 2017. "Yes, this is real. Measurable snow at #laketahoe in June happens about every 5-10 years," the National Weather Service office in Reno reported on Twitter.

Installation of Yosemite Half Dome cables delayed due to heavy snowpack in June 2017

The cables usually go up the Friday before Memorial Day. Not this year.
After a winter and early spring marked by unrelenting storms, massive amounts of snow delayed installation of the two metal cables that allow hikers to scale the last 400 feet to the summit without rock climbing equipment.
Completion of the installation didn't happen until early June.

A heat dome covers Northern California bringing record-breaking temperatures in late June 2017

A large bubble of hot air acted as a lid and prevented hot air from escaping while hovering over Northern California June 18 to 23, bringing temps in the 90s and low 100s. Two people died in San Jose as a result of the heat wave. (Photo: People lounge and play in Contra Loma Swim Lagoon to escape the 100 degree heat June 21, 2017 in Antioch)

The barrage of storms that pounded the Sierra Nevada this winter and spring added up to a snowpack that was massive.
Amid a major heat wave all of that snow melted fast. "The snow is inevitably going to melt and come down the mountain, but when you have a big snowpack like this, you expect higher than average runoff rates probably into August," Dave Rizzardo of the California Department of Water Resources said. "What the heat wave has done is accelerate this. It has compacted a lot of this runoff into this week." (Photos: Left: Sierra snowpack on March 1, 2017 at 184 percent of normal for this date. Middle: Sierra snowpack on June 6, 2017 at 177 percent of normal for this date. Right: Sierra snowpack on June 20, 2017 at 143 percent of normal for this date.)

Amid a heat wave marked by record-breaking temperatures, the Bay Area sky lit up on June 18 as lightning strikes cut through the clouds over the East Bay and North Bay.
"Thunderstorms of this nature aren't common in California in the late spring, but can occur several times a year," said Charles Bell, a meteorologist with the National Weather Service office in Monterey.

The trails are open but anything above 8,000 feet was covered in snow at the start of the season in June and requires technical skills and special equipment. The snowy conditions could easily persist through mid-July and even later in shady areas. "It’s more of a mountaineering experiencing out there in the Sierra," said Jack Haskel, information specialist for the Pacific Trail Association.

"The rafting season is usually 100 days in the summer, and this year we'll be lucky to get 20," said Aaron Rudnick, owner of Truckee River Raft Co. With Lake Tahoe nearly full, more water is being released into the Truckee River, creating high flows that can make going under bridges impossible. The season typically starts in June, but Rudnick expects to run boats for only a couple weeks in August.

With a massive winter snow pack, the slopes were open at Squaw Valley into July. This was only the fourth time the resort has been open for skiing in July.

Skiers are still hitting the slopes in July 2017

With a massive winter snow pack, the slopes were open at Squaw Valley into July. This was only the fourth time the resort has been open for skiing in July.

Photo: Rich Pedroncelli, Associated Press

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Lake Tahoe fills for the first time in 11 years in July 2017

On July 9, the lake level peaked at 6,229 feet, a hair shy of 6,229.1 feet above sea level, the point when it reaches full capacity. The last time it reached near full capacity was 11 years ago. The lake filled due to a winter season marked by high precipitation.

San Francisco gets scorched as new record-high temperature is set in September 2017

Many SF residents will remember where they were on Friday, Sept. 1, when the city was hit with heatwave that set a new record high temperature in the city — it hit 106 degrees in SF. The temperature was recorded by weather centers in downtown SF and at San Francisco International Airport. SF wasn't the only city in the Bay Area that experienced record-breaking heat over the Labor Day weekend. On Saturday, Sept. 2, Santa Cruz hit 110 degrees Fahrenheit, breaking a record that was set in 1904.

Spare the Air smog alerts were issued for the last day of August and the first four days of September 2017, amid the heat wave that swept through the Bay Area. The heat wave, combined with smoke from wildfires raging in Northern California and Oregon and light winds, prompted the consecutive smog alerts.

A powerful whirlwind called a gustnado touched down in California's Central Valley, near Buttonwillow, on Sunday, Sept. 3. The gustnado, which is a weaker form of a tornado according to the National Weather Service, was captured by Brent Rose, who was driving on Highway 33, 40 minutes northwest of Bakersfield. Rose, who said it was a very scary 20-minute weather event, captured a video of the gustnado.

A little less than three hours away from where the gustnado hit the Central Valley, another weird weather event took place at Santa Barbara's Hendry's Beach on Sunday, Sept. 3. Beach-goers were relaxing at Hendry's Beach the daybefore Labor Day when a bizzare microburst of rain and wind slammed the beach. According to some reports, wind gusts reached 80 mph and swept up beach umbrellas and chairs, while those at the beach took cover.

As the image above shows, two large sunspot groups were visible on the disk of the sun on Tuesday, Sept. 5. These were caused by two monster solar flares, coronal mass ejections, that hit Earth on Wednesday, Sept. 6. The solar flares caused high-frequency radio blackouts that lasted for about an hour, according to National Geographic. Also, the flares could make the Earth's auroras (also known as northern lights) visible in Northern California in the coming days.

Multiple wildfires in and around Yosemite National Park caused smoke to fill and choke the park, making its air quality unhealthy on Sept. 6. Many of Yosemite's most famous sights, like Half Dome and El Capitan, were obscured by the smoke. Mike Kochasic, a meteorologist with the National Weather Service, said that the high pressure weather system the region has experienced recently, mixed with the immense smoke, contributed to the lack of visibility and unhealthy conditions.

Early Monday, Sept. 11 a powerful wind storm swept through the Bay Area, with one 54 mph gust of wind being reported, while other areas were seemingly unaffected. The National Weather Service measured the gust at Pebble Beach at 2:30 a.m., while only 10 minutes away in Monterey conditions remained completely calm.

Amid severe thunderstorms, a water spout was spotted over Lake Tahoe on Sept. 13, spurring the National Weather Service to issue a tornado warning for several northeastern California counties and Carson City in western Nevada.
The rotating, funnel-shaped cloud, basically a tornado over water, touched down on the lake at about 4:27 p.m.
Tony Fuentes, a meteorologist with the service's Reno office, says water spouts on Lake Tahoe are rare and that since 2000 only five tornado warnings have been issued.

Wildfire smoke from North Bay fires chokes the Bay Area, air quality becomes worse than Beijing's in October 2017

San Franciscans woke up on Oct. 12 breathing air as polluted as that in Beijing, a city known for its suffocating gray haze.
Some people wore masks as they walked or rode their bikes to work—an uncommon sight in the Bay Area.
"These fires are bringing Beijing to the Bay Area and are allowing us to see what they experience around the clock," says Richard Muller, a UC Berkeley professor of physics who co-founded the site Berkeley Earth, which tracks air quality around the globe with an interactive map.

Northern California and Southern California saw two-plus weeks of dry weather in December due to a high pressure ridge parked along the West Coast. While Northern California did record rain in October and November, Southern California didn't see any and conditions remained dry as of the writing of this story on Dec. 14.

The city's air is typically damp and sticky with an average humidity of 75 percent as moisture sweeps in from the Pacific Ocean. Throughout the first half of December, humidity was frequently in the teens and even dropped below 10 in some cases as a high-pressure system blocked storms and kept moisture out. Many residents felt the impacts with chapped lips and dry skin.

Average rainfall for downtown San Francisco in February is 4.06 inches, and Rowe says there's a possibility we might not see a drop in the first three weeks.

The lack of rain is the result of the high-pressure ridge that is stretched along the entire West Coast and acting like an invisible wall blocking Pacific storms. These weather systems tend to be stable and persistent, and when strong, can endure for multiple weeks.